The present invention relates to a vacuum cleaner adapted to exchangeably accommodate a plurality of different types of suction nozzles, with a suction performance characteristic of an electric driven blower motor being controlled in dependence upon the type of suction nozzle employed or a surface to be cleaned.
In, for example, Japanese Laid-Open No. 280831/1986, a vacuum cleaner is proposed wherein a detecting apparatus detects a change in operation conditions of the vacuum cleaner and controls the electric driven blower motor in dependence upon the detected operating conditions by a detecting apparatus. Until now, an output of the electric driven blower motor has been controlled by a detecting apparatus such as, for example, a pressure sensor or the like.
However, no consideration has been given to an operation of a suction nozzle which represents the most suitable operation characteristic control for the vacuum cleaner depending upon the surface to be cleaned.
More particularly, no consideration has been given to the fact that different types of suction nozzles are used exchangeably with a single vacuum cleaner, or that the operation characteristic for the vacuum cleaner can be affected by the air flow amount in a case wherein the filter member of the cleaner is clogged.
In this connection, the air flow range during actual use of a vacuum cleaner differs in dependence upon the type of suction nozzle used such as, for example, a suction nozzle 7 having a large opening area for general floor use and a narrow suction nozzle having a small opening area such as a crevice suction nozzle 8 as shown in FIG. 2.
In FIG. 3, graphically depicting an aerodynamic characteristic of the suction nozzle 7, a curve P1 represents an output static pressure curve of the electric driven motor, and curves A1, A2 represent the ventilating air loss pressure of the suction nozzle 7 when the filter member of the vacuum cleaner is not clogged.
As shown in FIG. 3, in the vacuum cleaner using the suction nozzle 7, the curve A1 is a lower limit value of the air flow amount or rate Q(a) with a non-clogged filter and the curve A2 is an upper limit value of the air flow amount Q(a) with a non-clogged filter. In FIG. 3, .DELTA.H1 represents a fluctuating width in the static pressure H with the suction nozzle 7 and .DELTA.Q1 represents a fluctuating width in the air flow amount Q(a) with the suction nozzle 7.
When the suction nozzle 7 moves on the surface to be cleaned, the contacting condition of the suction nozzle 7 with the surface to be cleaned changes and the ventilating air resistance e.g. the resistance to air being suctioned by the blower motor of the vacuum cleaner through the suction nozzle, changes and results in fluctuation of the static pressure H and the air flow amount Q between the curves A1, A2 as shown in FIG. 3
The ventilating air loss at the suction nozzle portion is reduced in accordance with the reduction of the air flow amount Q. The static pressure fluctuating width .DELTA.H1, e.g. the amount of the static pressure fluctuation .DELTA.H1, representing a-difference between the curves A1 and A2, and which is the fluctuating width of the ventilating air loss pressure at the suction nozzle 7 depending upon the cleaning operation, is small, and the curves A1 and A2 nearly approach one another as the static pressure fluctuating width .DELTA.H1 approaches a small air flow range as shown in FIG. 3.
In FIG. 3, the curves B1, B2 represent the ventilating air loss pressure when the filter member of the vacuum cleaner is clogged and, as compared with the curve A1 and A2, the value of the ventilating air loss increases due to the clogging of the filter member.
As shown in FIG. 3, the curve B1 represents a lower limit value of the air flow amount Q(b) during a clogging of the filter member and the curve B2 represents an upper limit value of the air flow amount Q(b) during a clogging of the filter member.
The difference between the curves B1, B2 is the fluctuating width and also is the pressure loss fluctuating width at the suction nozzle portion corresponding to each air flow amount Q(b). Further, the air flow amount Q(b) shows the lower limit of the actual dust suction performance of the vacuum cleaner.
In actual use, the vacuum cleaner having the suction nozzle 7 has a range between an air flow amount Q(a) and the air flow amount Q(b) as shown in FIG. 4. The non-use range of the vacuum cleaner having the suction nozzle 7 is less than the air flow amount Q(b) as shown in FIG. 4.
In FIG. 4, a curve P2 indicates a suction performance characteristic during a strong operation having 100 volts for the vacuum cleaner and a curve P2 indicates a suction performance characteristic during a weak operation having 50 voltage for the vacuum cleaner, respectively.
The aerodynamic characteristic with the crevice nozzle mounted on the cleaner main body is shown in FIG. 5. When the output static pressure curve P3 of the electric driven blower motor is the same as the curve P1 of FIG. 3, since the opening area of the crevice nozzle 8 is small, the ventilating air loss pressure is large. In the vacuum cleaner using the crevice nozzle 8, as shown in FIG. 5, the curve C1 is a lower limit value of the air flow amount Q(c) during no clogging of the filter member and the curve C2 is an upper limit value of the air flow amount Q(c) during no clogging of the filter member. .DELTA.H2 is a fluctuating width in the static pressure H due to the crevice suction nozzle 8, and .DELTA.Q2 is a fluctuating width in the air flow amount Q(c) due to the use of the crevice nozzle 8.
Therefore, even when the filter member of the cleaner main body is not clogged, the ventilating air loss pressure is large as shown by the curve C1, and even at the maximum air flow amount condition when the crevice nozzle 8 is lifted from the cleaning portion to be cleaned, it has an air flow amount Q(c). This value is substantially equal to or above the lower limit of the air flow amount Q(b) under the actual range of the air flow amount shown in FIG. 3.
As shown in FIG. 5, a curve D1 is a lower limit value of the air flow amount Q(d) during a clogging of the filter member and a curve D2 is an upper limit value of the air flow amount Q(d) during clogging of the filter member. The actual use range of the vacuum cleaner employing the crevice nozzle 8 is a range which is between the air flow amount Q(c) and the air flow amount Q(d) as shown in FIG. 6. The non-use range of the vacuum cleaner using the crevice nozzle 8 is a range which is less than the air flow amount Q(d) as shown in FIG. 6.
The curve C2 shows the fluctuating upper limit side ventilating air loss pressure when the crevice nozzle 8 is moved on the cleaning portion to be cleaned. Since the opening area of the crevice nozzle 8 is small, the opening area of the crevice nozzle 8 adheres closely to the portion to be cleaned and, at this time, the ventilating air loss has a large value. The fluctuating widths in the curve C1 and C2 have values larger than the fluctuating widths in the curve A1 and A2 in the general floor nozzle 7.
When the filter member is clogged, the lower limit value of the air flow amount in the actual use range equals the air flow amount Q(d). At that time, the ventilating air loss pressure curve line is indicated by the curve D1, and the fluctuating upper limit side ventilating air loss pressure curve is indicated by the curve D2.
As stated above, the air flow amount range Q(a)-Q(b) is the actual use range of the suction nozzle having the large opening area as shown in the general floor nozzle 7 and differs from the air flow amount range Q(c)-Q(d) in the actual use range of the suction nozzle having the small opening area as represented by the crevice nozzle 8. Comparing the representative examples shown in FIG. 3 and FIG. 5, it is clear that the air flow amount Q(a)&gt;the air flow amount Q(c), and the air flow amount Q(b)&gt;the air flow amount Q(d).
The actual use range which is the above stated actual use possible air flow amount range and the non-use range which is the non-use range taking into account the lowering of the dust suction performance are shown in FIG. 4 and FIG. 6 corresponding to FIG. 3 and FIG. 5.
As shown in FIGS. 4 and 6, in the air flow amount ranges greater than the air flow amounts Q(a) and Q(c) which are out of the actual use range, and in the air flow amount ranges less than the air flow amounts Q(b) and Q(d), by decreasing of the suction performance, the an electric power saving and a noise reduction for the vacuum cleaner are attained.
So as to obtain the above stated desired suction performance, the control for the suction nozzle is carried out, as easily understood when FIG. 4 and FIG. 6 are superposed as shown in FIG. 7, by only one suction performance characteristic with which the characteristics of the two suction nozzles are compatible.
Namely, in an air flow amount range less than the air flow amount Q(b), the suction performance characteristic decreases the suction force. For the suction nozzle having the small opening area such as the crevice nozzle 8, since the control for lowering the suction force is carried out early, e.g. before the air flow amount is reduced to Q(d) the suction force may become weak during the actual use range.
Additionally, in the air flow amount range less than air flow amount Q(d), the suction performance characteristic decreases the suction force. For the suction nozzle having the large opening area such as the suction nozzle 7, a problem arises in that there may be an insufficient dust suction force.
Even with the most suitable air flow amount for the general suction nozzle 7, the ventilating air loss pressure is large for the suction nozzle 8; therefore, problems arise with respect to an overheating of the electric blower motor thereby reducing the service life thereof.
Moreover, even with the most suitable air flow amount for the suction nozzle 8, a problem arises with respect to the suction nozzle 7 due to an insufficiency in the suction air flow amount thereby lowering the suction performance.
In the above described conventional techniques, only one type of operation characteristic is taken into account with respect to the cleaning surface to be cleaned, namely, the different natures of the surface to be cleaned such as tatami, floor and carpet. Accordingly, for example, little consideration is given to the careful suction performance characteristic control suited to the respective nature of the surface to be cleaned.
The electric driven blower motor in the prior art vacuum cleaner employs a chopper control system inverter driven brushless direct motor. Such a chopper control system inverter driven brushless direct motor is disclosed in, for example, Japanese Patent Laid-Open No. 214219/1985. In this type of vacuum cleaner, a predetermined suction force is obtained in dependence upon a control of a control for the rotational speed of the brushless direct motor.
Furthermore, in the above noted vacuum cleaner employing the chopper control system inverter driven brushless direct current motor, no attention has been given to protection during the over-load operation and the high speed rotation prevention of the motor.